Molecular Entomology 2024, Vol.15, No.1, 32-42 http://emtoscipublisher.com/index.php/me 36 association studies on a global rice germplasm collection. The Bph37 gene, along with other resistance loci, showed high nucleotide diversity and ancient balancing selection, indicating its long-term effectiveness in providing resistance against various BPH biotypes (Zhou et al., 2021). Figure 2 Schematic representation of host-induced gene silencing in insects through siRNA approach (Adopted from Bentur et al., 2020) Image caption: (1) Integration of insect gene-targeted siRNA cassette (transgene) into rice genome; (2) fate of transgene in rice cells; (3) expression of transgene in rice cell generates the mRNA; (4) formations of dsRNA through self-complementation of transgene’s sense and antisense strands in rice cell; (5) host Dicer-mediated specific cleavage of dsRNA leads to production of siRNAs in rice cell; (6) host-generated siRNAs processed by host Argonaute protein (the main component of RNA-induced silencing complex or RISC); (7) host-generated siRNAs are nonfunctional in rice cells due to absence of targeted gene; (8 and 9) host-synthesized dsRNAs/siRNAs transfer from rice plant to insect through feeding on rice tissues; (10) fate of transferred dsRNA/siRNAs in insect cells; (11) generation of siRNAs from dsRNA through insect Dicer-mediated cleavage; (12) the siRNAs are processed by insect Argonaute proteins/RISC complex; (13a) formation of activated RISC along with target-specific guide RNA; (13b and 13c) the passenger RNA is separated from guide RNA and degraded; (14) transcription of insect DNA resulted in the expression of targeted functional mRNA (transcript); (15) guide strand of siRNA helps in identification and binding of activated RISC to the targeted mRNA; (16) silencing of targeted gene expression by RISC-mediated cleavage of corresponding mRNA (Adopted from Bentur et al., 2020) A third example is the discovery of the Bph38 gene from the wild rice species Oryza rufipogon Griff. This gene confers high resistance to both brown planthopper and white-backed planthopper. Near-isogenic lines carrying Bph38 were developed, showing strong resistance and desirable agronomic traits, making this gene a valuable resource for breeding insect-resistant rice varieties (Yang et al., 2020).
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